HBM3 was mentioned in presentations by Samsung and SK hynix at the Hot Chips Symposium last year. It is claimed HBM3 would improve on density, bandwidth, cost, and power consumption but there were few other details.
Samsung's HBM3 presentation hinted that HBM3 density would be 2x or better, peak bandwidth would be 2x or better and IO/Core voltage would be "much less", compared to HBM2.
Now Hexus has dug up some more HBM3 details from a Rambus investor meeting earlier this week. The release of HBM3 product is quite a way off but a key slide shows the bandwidth of HBM3 is 4000Mbps. Rambus said that the design complexity goes up. HBM3 has a higher stack height.
HBM3 will be made on the 7nm node. And 7nm semiconductor products will not be around until 2019.
Rambus also mentioned DDR5. It claimed that DDR5 will deliver an expected bandwidth of 4800 - 6400Mbps. Like HBM3, it is set to be fabricated at 7nm.
DDR5 is said to deliver double density, double bandwidth, and greater efficiency than its predecessor. At the time of that report it was estimated that DDR5 could reach the market by 2019.